1. Technical Field
The present invention relates to a screen unit.
2. Related Art
A screen unit is known as a unit provided with a screen which reflects projection light projected from a projection type display apparatus such as a projector to display an image. A certain type of the screen unit generally known has a link mechanism which moves the screen upward and downward. This screen unit further has a housing which accommodates the link mechanism and the screen. For moving the screen upward and downward, the screen unit opens and closes a cover provided on the housing. Generally, this cover is manually opened and closed by the operation of a user. However, there is a type of screen unit capable of opening and closing the cover by actuation of a motor or other devices.
JP-A-2002-49099 discloses a cabinet for a screen unit provided with a screen accommodated within a cabinet main body. A top plate provided on the upper surface of the cabinet main body has an opening opened and closed by a cover. According to this structure, the position of the screen switches between an expanding condition in which the screen stands through the opening and expands in a flat shape, and a storing condition in which the screen is stored within the cabinet main body positioned below the opening.
Another reference JP-A-8-262574 discloses a reflection type projection screen which has a storage case and a stand. A storage case main body of the storage case has a storage case portion which accommodates a screen main body of the reflection type projection screen, and a cover which opens and closes the storage case portion. The storage case main body further has a cover closing operation temporary stop mechanism which stops and suspends the rotation of the opened cover in the cover closing direction.
According to the cabinet disclosed in JP-A-2002-49099, the method for opening and closing the cover is not specifically described. On the other hand, as for the screen disclosed in JP-A-8-262574, the opening and closing operation of the cover and the upward and downward movement of the screen are performed by different independent mechanisms.
In case of a screen unit whose cover is manually opened and closed, the cover is often left unclosed due to the troublesome operation for opening and closing the cover. When the cover remains unclosed, dust adheres to the screen accommodated in the housing and causes degradation of images projected on the screen in some cases. On the other hand, in case of a screen unit which opens and closes the cover by the operation of a motor, the opening and closing mechanism required for this purpose raises the cost.
Accordingly, development of such a screen unit has been demanded which has a simple structure for opening and closing the cover and prevents an unclosed condition of the cover left without notice.